Rutherford B. Hayes Library Visited by Light-Fingered Trio

Some say that President Hayes stole the 1876 election from his Democratic opponent, Samuel Tilden, but now it's the Hayes Library that has suffered a loss. Two of the Rutherford B. Hayes Presidential Center Library's rarest books, with a total value of about $130,000, are missing.

While authorities have arrested three people believed connected to the disappearances, it's still not known where the books are. The books are the Maxwell Code and the Freeman Code, some of Ohio's first laws, dating back to the 1790's.

One of the thieves was previously arrested in 2007 in connection with the theft of $20,000 worth of antique maps from a bookstore in Harrisburg, IL. He also has a prior arrest record for felony theft and receiving stolen property. Toledo Blade reports.

Once again here is an account of library thieves, and the photos of the perpetrators were not published. Perhaps they could be published after they are tried, but at least one of them had been convicted before, so his mug shot is public property and can be published anytime.
Libraries are far too often handicapped in that the library thieves are never identified by published photographs, so other librarians can see if they may have been hit, too.

I'd be interested to know how this happened. Granted, libraries can't prevent 100% of thefts. However, I worked in special collections for 6 years with some EXTREMELY valuable items, and I didn't let them out of my sight. In order to look at our most valuable books, there had to be a staff member sitting across from the patron at all times, basically staring them down. The way our library facility and policies were designed, it would have been very difficult to do the snatch-and-run number, or the slip-it-in-the-backpack trick.

whether they be rare, expensive or unique to the degree that these recently lost items are you should literally stand over them or have them in a location where they are totally monitored.
If you don't do that then you are asking for trouble.

If you don't have a special space to allow you to do that then you have to change the way you work. Make people make appointments with contact details etc you can check on in advance.

Or of course if possible start digitising these materials so you don't need to get these rare, expensive items out that often.